Two challenges should be overcome for the ultra‐precision machining of micro‐optical element with freeform curved surface: one is the intricate geometry, the other is the hard‐to‐machining optical materials due to their hardness, brittleness or flexibility. Here scanning electrochemical probe lithography (SECPL) is developed, not only to meet the machining need of intricate geometry by 3D direct writing, but also to overcome the above mentioned mechanical properties by an electrochemical material removal mode. Through the electrochemical probe a localized anodic voltage is applied to drive the localized corrosion of GaAs. The material removal rate is obtained as a function of applied voltage, motion rate, scan segment, etc. Based on the material removal function, an arbitrary geometry can be converted to a spatially distributed voltage. Thus, a series of micro‐optical element are fabricated with a machining accuracy in the scale of 100 s of nanometers. Notably, the spiral phase plate shows an excellent performance to transfer parallel light to vortex beam. SECPL demonstrates its excellent controllability and accuracy for the ultra‐precision machining of micro‐optical devices with freeform curved surface, providing an alternative chemical approach besides the physical and mechanical techniques.

中文翻译：

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用于自由曲面微光学元件超精密加工的扫描电化学探针光刻


自由曲面微光学元件的超精密加工需要克服两个挑战：一是复杂的几何形状，二是光学材料由于其硬度、脆性或柔性而难以加工。这里开发了扫描电化学探针光刻（SECPL），不仅可以通过3D直写来满足复杂几何形状的加工需求，而且可以通过电化学材料去除模式来克服上述机械性能。通过电化学探针施加局部阳极电压来驱动GaAs的局部腐蚀。材料去除率是作为施加电压、运动速率、扫描段等的函数而获得的。基于材料去除函数，可以将任意几何形状转换为空间分布的电压。由此，一系列加工精度达到100纳米级的微光学元件被制造出来。值得注意的是，螺旋相位板在将平行光传输到涡旋光束方面表现出优异的性能。 SECPL在自由曲面微光学器件的超精密加工中展现了优异的可控性和精度，为物理和机械技术之外的化学方法提供了替代方案。